Am I missing anything for strengthening a 915?

[TMo]

I'm planning on having a spare 915 rebuilt for strength and long life.

Right now I'm planning on adding a billet side-plate with the 930 bearing, LSD (haven't decided between Clutch type or torque biasing), Billet bearing plate, External cooling pump with internal spray-bar and a Wevo internal shift gate.

The car will be 100% street driven, but I plan to put a lot of miles on the car, both highway and surface roads.

Am I missing anything on building a box for strength and long life?

[gled49]

915’s start in 72 and go thru 86. What year u got?

[TMo]

The spare is from 1980 I believe, part # 915-63. The seller swears it's in usable condition. The drain plug was clean, and a peek inside after taking the side-plate off looked good, so I'm hoping the seller was right, and the rebuild will be straightforward.

[-Levi-]

Op, good work and good list of upgrades. I’m actually doing the same thing with the sane upgrades.
From my research you are pretty close to the reasonable limits, you could go hardened gears that are cryo treated… but let’s be real, that doesn’t make financial sense.

You can upgrade to larger 964 axles, it’s not super strait forward and it’s expensive.. just to add something extra.

[winders]

Skip the cooler unless you are doing races longer than 45 minutes. You said it’s a street car so you probably are not…

[stownsen914]

What kind of power/torque are you expecting to put through it? 915s despite their reputation can withstand a lot if not abused, especially under 300 hp ish

[Dpmulvan]

Originally Posted by TMo

The spare is from 1980 I believe, part # 915-63. The seller swears it's in usable condition. The drain plug was clean, and a peek inside after taking the side-plate off looked good, so I'm hoping the seller was right, and the rebuild will be straightforward.

They always swear they’re usable. Better do a price check on synchros, bearings et you might be approaching g50 money by the time your done.

[TMo]

Originally Posted by winders

Skip the cooler unless you are doing races longer than 45 minutes. You said it’s a street car so you probably are not…

Am I mistaken in thinking it would prolong life on a street car?

Originally Posted by stownsen914

What kind of power/torque are you expecting to put through it? 915s despite their reputation can withstand a lot if not abused, especially under 300 hp ish

The engine should produce around 300+/- HP and apx. 350 TQ, I drive with mechanical sympathy, but I'd like as much strength as practical to back it up. I don't drag race, and I'm not prone to hooning.

Originally Posted by Dpmulvan

They always swear they’re usable. Better do a price check on synchros, bearings et you might be approaching g50 money by the time your done.

Yeah, always a concern, but I'm crossing my fingers, the car it came from was totaled at about 70K miles due to a tree falling on it. (I saw the car being parted when I picked the box up) Probably should have mentioned that... but of course, all bets are off with used parts. Most of the parts won't be ordered until the box has been opened up and inspected by the rebuilder.

[stownsen914]

350 torque is a lot the subject a 915 to. At a certain level parts can simply fail due to the raw twisting force applied to them. You’re right to beef up the trans if that torque number is accurate. What’s the motor?

[TMo]

The motor is a 2.0 Ecotec turbo. The motor will have 3 levels of tune available at the push of a button, the 300/350 tune is the top level I plan to run, The car will default to a lower level tune on cold starts, and I expect to do a fair bit of my driving at the 260/260 default level.

I also plan to limit first gear torque to 275 ft/lb regardless of tune.

[Matt Monson]

More power generate more heat. I see no downside to the spray bar and cooler.

[917_Langheck]

Contact Matt Monson here on PP, he'll have some ideas for you.

[winders]

Originally Posted by TMo

Am I mistaken in thinking it would prolong life on a street car?

Well, it wasn't clear you were going to be putting a GM turbocharged engine behind it.

I wouldn't be using a 915 for this application....I'd use a 930 with a short bell housing.

[PeteKz]

Originally Posted by Matt Monson

More power generate more heat. I see no downside to the spray bar and cooler.

Paying for it.

[TMo]

I appreciate the input from everyone. I guess maybe a 930 would make more sense, but the 915 is what I have for the moment, so I'm hoping I can build it enough to be reliable.

I know a bunch of the hotrod and outlaw guys are running more powerful engines than mine will be; any given 350 V8 is putting down more torque than I'll ever imagine.

I guess I'll just cross my fingers, but I'll keep my eyes out for a 930, just in case.

[917_Langheck]

Originally Posted by TMo

I know a bunch of the hotrod and outlaw guys are running more powerful engines than mine will be; any given 350 V8 is putting down more torque than I'll ever imagine.

I guess I'll just cross my fingers, but I'll keep my eyes out for a 930, just in case.

I know of one of these with a '73 915. It's always easy does it. The difference in torque profile between the flat 6 and the V8 can be fairly vast, and the 915 is no M22.

[Matt Monson]

Originally Posted by PeteKz

Paying for it.

Building a custom Porsche hot rod isn’t cheap.

[Tyson Schmidt]

Speaking of 930, nobody mentioned the 930 dogteeth and synchro upgrade. 3rd gear is especially weak due to the small size of the drive gear, which leaves the dogtteth overhanging the gear by quite a bit.

The 930 dogteeth have an additional annular ring running under the dogteeth, significantly inreasing the torque capacity. You'll need the dogteeth, and all the 930 hardware that goes with them, and the synchros. The slider is the same.

[PeteKz]

Originally Posted by Matt Monson

Building a custom Porsche hot rod isn’t cheap.

Oh, I know that. . But his car is "100% street." Seems like overkill, and there are better ways to spend the money on the car. But hey, it's always easy to spend OPM!

[Matt Monson]

Originally Posted by PeteKz

Oh, I know that. . But his car is "100% street." Seems like overkill, and there are better ways to spend the money on the car. But hey, it's always easy to spend OPM!

It’s always the street car guys who burn up 5th gear, with oil starvation. A spray bar is not an extraneous mod.

And let’s not forget the euro Carreras got a cooler stock.